The invention relates to a mechanical joint for collapsible structures. U.S. Pat. No. 5,681,231 discloses a collapsible structure, in particular a game goal, with an elbow joint having an arm with a gap therein. A frame member inserts into the gap in a fixed or upright position and is removed from the gap to collapse the structure. A flexible member connected to the frame member and the portion of the elbow having the gap allows the frame member to move into and out of the joint while remaining connected to the overall structure.
U.S. Pat. No. 6,220,776 discloses a corner or straight joint for a collapsible structure with a socket portion that accommodates a moveable member with multiple degrees of motion. In this joint the moveable member is connected with a threaded or otherwise twistable connection to the rod of a heim joint which rotates on a roll pin. The moveable portion moves in and out of the socket portion to erect and collapse the structure, as frame members are attached to the fixed and moveable portions of the joint.